Damping Analysis of Unidirectional Carbon/Flax Fiber Hybrid Composites

Abstract

The purpose of the present paper is to study the effect of hybridation, stacking sequences and fiber orientation on the damping properties of unidirectional carbon/flax fiber reinforced epoxy composites. Non-hybrid and hybrid laminates with different stacking sequences were produced by molding vacuum process. Free vibration tests with an impulse technique were performed on test specimens to investigate the dynamic behavior. Finite element analysis was used to model damping to evaluate the different energies dissipated in the material layer directions of the carbon/flax composites. Close agreement was found between the experimentally measured values and those derived from the numerical simulation for the damping coefficients. The results obtained show that flax layers had a significant effect on damping properties.

Review on Hybrid Carbon/Flax Composites and Their Properties

“…A hybridisation of carbon with flax fibers to improve the damping properties of carbon composites is promoted by the high damping ratio of flax fibers in comparison with titanium, aluminium, steel, or carbon [8]. Furthermore, the damping of nonhybrid flax fiber laminates is significantly higher than the damping coefficients of nonhybrid carbon fiber laminates [24]. Particularly, the damping coefficient of composites reinforced with flax fibers is found to be 4 times higher than that of composites reinforced with carbon fiber 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 [8,9,12,13,15,17,21,22,26,40,43,45,46,[51][52][53][54][55].…”

“…As an example, in the case of UD nonhybrid flax composites and UD hybrid carbon/flax composites with outer flax layers, the maximum damping is achieved in the case of the 75°fiber alignment. On the other hand, in the case of UD nonhybrid carbon fiber composites and UD hybrid carbon/flax composites with outer carbon layers, the highest damping is achieved in the 45°fiber alignment [24].…”

“…Besides the flax fiber content, the stacking sequence has a significant influence on the damping properties of carbon/flax composites. The hybrid composites with outer layers made of carbon fibers have lower damping than the hybrid composites with outer layers made of flax, since the energy dissipation is directed mainly by external layers of the composites [14,24]. In comparison with nonhybrid carbon composites, the damping of a hybrid composite with outer layers made of carbon is about 6% higher.…”

“…International Journal of Polymer Science own internal standards, which may significantly differ from one another. The review of the reported studies on the carbon/flax composites shows that in the cases where the predrying of flax takes place, the conditions vary from drying at 60°C for 15 min [21] to drying at 110°C for 1 h [24] or at 80°C for 24 h [22] or at 90°C for 3 h [25]. Certainly, these differences have a certain influence on the properties of the resulting composites, because drying affects the mechanical properties of the natural fibers themselves.…”

“…Therefore, through friction between and within the cell walls, the structure of flax fibers promotes dissipation of energy and leads to an enhanced intrinsic damping in comparison with synthetic fibers [57]. Among various methods available for the testing of damping, free flexural vibration testing is mostly used in the case of the reported carbon/flax hybrid composites [8,14,17,18,24]. The reported results show that the damping properties of carbon-/flax-epoxy composites depend on the fiber content, stacking sequence, and fiber direction.…”